A Plea For More Post-Release Research In Wildlife Rehabilitation
When I worked as a wildlife veterinarian I found it challenging, because I mostly didn’t know if my patients lived beyond their release back into the wild. With prayers and well-wishes, I sent them on their way back into the forest, the river, or the sky, hoping they would thrive in their second chance at life.
Every year, wildlife rehabilitators release thousands of previously injured, sick, or orphaned animals back into the wild. Even though wildlife rehabilitation has been gradually progressing as a profession since the early 1980’s (complete with certification, national and international organizations, and continuing education courses), very little is known about post-release survival of rehabilitated wildlife (Kelly, Scrivens, & Grogan, 2010). If the rehabilitated animals we judge healthy enough to be released do not, in reality, have the necessary skills or stamina to survive and prosper in appropriate habitat, their welfare may be greatly compromised following release (Kelly, Scrivens, & Grogan, 2010). The fundamental goal of wildlife rehabilitation is to give every animal the best chance for post-release survival in their natural habitat.
Why We Need Post-Release Research
Wildlife rehabilitation is costly in terms of financial support and human resources, but most people would agree that it is a worthwhile endeavor. The field of wildlife rehabilitation likely started when compassionate humans first encountered wild animals who were injured or orphaned due to anthropogenic causes. Stakeholders now include not only the rescued animal and rehabilitator, but also conservationists, biologists, and the public.
It is now more important than ever to find out if we are reaching our goal of every released animal living well and normally after release. We need data from more post-release studies to investigate the animal welfare perspective (thriving or suffering), the financial perspective (resource costs for successful releases), and the scientific perspective (continual reform of best rehabilitation protocols, and how released individuals integrate into resident populations).
Post-Release Studies Done Well
Oil spills and resultant oiled wildlife present a good case study to consider. In every oil spill extending back to the Exxon Valdez spill in Prince William Sound, Alaska in 1989, and continuing to the present, how we respond to oiled wildlife has become controversial and newsworthy (Holcomb, 2010). Images on TV or the internet of oiled pelicans, turtles, and sea otters evoke public interest and sympathy. Wildlife rehabilitators specializing in oiled wildlife turn out to triage, clean, and further rehabilitate the oiled victims.
Soon the skeptics and critics surface; they maintain that cleaning and release of oiled wildlife is a waste of time. They say resources focused on individual animals (as opposed to populations) are misspent, and the most responsible course of action is to immediately euthanize affected animals (Henkel & Ziccardi, 2018). To make their point they often cite an outdated 1996 post-release survival study of oiled, cleaned seabirds in North America by Oregon biologist Brian Sharp (Sharp, 1996). This post-release research study concluded that oiled seabirds should not be rescued, treated, and cleaned since post-release survival rates were so low.
But since then, things started to change for the better. Variables such as protocols used to clean and care for the oiled birds, experience of the organization caring for the oiled birds, assessment methods for health and waterproofing prior to release, and techniques for tracking released animals were recognized, examined and improved relative to the early rehabilitation attempts and resultant studies.
Many newer studies using radio telemetry, satellite tracking, microchip tracking, visual observation of long-term breeding colonies, and band recovery have concluded that many seabirds not only survive the oiling and rehabilitation process, but also breed successfully for many years (Holcomb, 2010).
For example, a 2014 New Zealand study of oiled and rehabilitated little blue penguins tracked via microchip for 23 months after release showed no significant difference between rehabilitated birds and control birds in terms of post-release survival and breeding productivity (Sievwright, 2014). A study of 182 oil-rehabilitated Brown Pelicans translocated from the area of the 2010 Deep Water Horizon Spill to an area non-impacted by oil, revealed that over the course of the 6-week monitoring period no mortality of rehabilitated birds was documented. The translocated Brown Pelicans readily integrated with local pelican flocks (Sellman, Hess, Salyers, & Salyers, 2012).
A growing number of studies since 1996 have shown that a bird’s survival may be related to how a particular species copes with the stress of oiling and subsequent rehabilitation; and the reported overall survivorship across species has greatly surpassed Sharp’s bleak calculations (Holcomb, 2010). The more we learned from the post-release studies, the better we became at rescuing, cleaning, rehabilitating and releasing oiled wildlife.
Individual Animals And Managed Populations
During a storm in February 1999, a freighter named the “New Carissa” ran aground on a beach near Coos Bay, Oregon. It broke apart and released fuel oil into the water creating one of the most serious oil spills ever affecting Oregon. The endangered Western Snowy Plover population in Coos Bay was only 30 to 45 birds at the time. Oil spill response teams captured 31 of the oiled birds, and all were successfully rehabilitated and released. Since their numbers are so low, this species is monitored closely. Post-release data showed no difference in the mortality of the released, previously-oiled birds to those never oiled (Holcomb, 2010). The US Department of the Interior reported that between 4 and 8 Western Snowy Plovers were killed in the spill (Skrabis, 1999). Each individual Plover’s life is considered valuable to the conservation of the entire species.
The plight of the Western Snowy Plover may be repeated in other groups of struggling wildlife as human population expands into, exploits, and fragments the natural habitat of wild birds, mammals, reptiles, amphibians, and fish. There has been controversy between conservationists and wildlife rehabilitators whether rehabilitating the individual animal makes a difference. It certainly makes a difference to that animal, and as wildlife numbers dwindle worldwide, it increasingly makes a difference to the survival of populations in decline.
Eventually many wildlife populations will likely be managed in some capacity by teams made up of wildlife rehabilitators, wildlife and zoo veterinarians (as zoos expand their conservation and rehabilitation efforts), biologists, and private or governmental organizations. Already this is the case with the endangered wild Orcas of the Pacific Northwest. Numbers have become small enough (about 75) that individuals are numbered, named and monitored; and they are starving to death due to the decline of chinook salmon. In the summer of 2018, wild Orca mom J35 swam hundreds of miles carrying her dead calf for 17 days as the world watched and mourned with her. Simultaneously the National Oceanic and Atmospheric Administration Fisheries attempted to feed live chinook dosed with medicine to sick and starving wild Orca J50 from the same pod (Mapes, 2018). Every individual counts in this managed population.
Justification And Evaluation
Now more than ever before, the wildlife rehabilitation community has a responsibility to show that post-release survival of rehabilitated wildlife is successful, in order to justify the rehabilitation process. Whether the rehabilitated animal is a plentiful Eastern Cottontail rabbit or a critically endangered Hawksbill sea turtle, we owe him or her the best possible second chance at life. Any effective program should involve regular reflective evaluations of worth and improvement. More post-release studies, please.
Henkel, L., & Ziccardi, M. H. (2018). Life and Death: How Should We Respond to Oiled Wildlife?
Holcomb, J. (2010, June 10). Every Bird Matters.
Kelly, A., Scrivens, R., & Grogan, A. (2010). Post-release survival of orphaned wild-born polecats Mustela putorius reared in captivity at a wildlife rehabilitation centre in England.
Mapes, L. (2018, August 7). NOAA plans ‘outside the box’ response to save J pod orca, which may have just days to live.
Sellman, W., Hess, T. J., Salyers, B., & Salyers, C. (2012). Short-term response of Brown Pelicans (Pelecanus occidentalis) to oil spill rehabilitation and translocation.
Sharp, B. E. (1996). Post-release survival of oiled, cleaned seabirds in North America.
Skrabis, K. E. (1999). Resource Equivalency Analysis for Western Snowy Plover.